Chemistry of
Life
1
Water
• About 60-90 percent of an organism is water
• Water is used in most reactions in the body
• Water is called the universal solvent
• Water properties:
– Polarity
– Cohesivness
– Adhesivness
– Surface Tension
2
Organic Compounds
• Compounds that contain
CARBON are called organic.
3
Carbon (C)
• Carbon has 4 electrons in it’s
outer shell.
• Carbon can form covalent bonds
with as many as 4 other atoms
(elements).
• Usually with C, H, O or N.
• Example:
CH4(methane)
4
Macromolecules
• Large organic molecules.
• Also called POLYMERS.
• Made up of smaller “building blocks”
called MONOMERS.
• Examples:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids (DNA and RNA)
5
Question:
How Are
Macromolecules
Formed?
6
Answer: Dehydration Synthesis
• Also called “condensation reaction”
• Forms polymers by combining
monomers by “removing water”.
HO
H
HO
H
H2O
HO
H
7
Question:
How are
Macromolecules
separated or
digested?
8
Answer: Hydrolysis
• Separates monomers by “adding
water”
HO
H
H2O
HO
H
HO
H
9
Carbohydrates
10
Carbohydrates
• Small sugar molecules to large sugar
molecules.
• Americans consume an average of 140
pounds of sugar per person per year
• Examples:
A. monosaccharide
B. disaccharide
C. polysaccharide
11
Carbohydrates
Monosaccharide: one sugar unit
Examples:
glucose
glucose (C6H12O6)
deoxyribose
ribose
Fructose
Galactose
12
Carbohydrates
Disaccharide: two sugar unit
Examples:
– Sucrose (glucose+fructose)
– Lactose (glucose+galactose)
– Maltose (glucose+glucose)
glucose
glucose
13
Carbohydrates
Polysaccharide: many sugar units
Examples: starch (bread, potatoes)
glycogen (beef muscle)
cellulose (lettuce, corn)
glucose
glucose
glucose
glucose
cellulose
glucose
glucose
glucose
glucose
14
Cellulose
• Cellulose is not a nutrient for humans, but
it is an important part of a healthful diet
• Most fresh fruits, vegetables, and whole
grains are rich in cellulose
• Some microbes can break down cellulose
into glucose monomers
• Cellulose, found in plant cell walls, is the
most abundant organic compound on Earth
15
• Cows harbor cellulose-digesting bacteria in their
stomach to hydrolyze the cellulose of hay and
grass to convert the glucose to other nutrients
that nourish the cow
•Termites also have cellulose
digesting microbes within
their gut because they are
unable to digest it by
themselves.
•Some fungi can also digest
cellulose, helping recycle
chemical elements within the
Earth’s ecosystem
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Lipids
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Lipids
• General term for compounds which are
not soluble in water.
• Lipids are soluble in hydrophobic
solvents.
• Remember: “stores the most energy”
• Examples: 1. Fats
2. Phospholipids
3. Oils
4. Waxes
5. Steroid hormones
6. Triglycerides
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Lipids
Six functions of lipids:
1. Long term energy storage
2. Protection against heat loss
(insulation)
3. Protection against physical shock
4. Protection against water loss
5. Chemical messengers (hormones)
6. Major component of membranes
(phospholipids)
19
Lipids
Triglycerides:
composed of 1 glycerol and 3
fatty acids.
H
O
H-C----O C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
O
H-C----O C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
O
fatty acids
H-C----O C-CH -CH -CH -CH
2
2
2
H
glycerol
20
Fatty Acids
There are two kinds of fatty acids you may see
on food labels:
1. Saturated fatty acids: no double bonds
(bad)
O
saturated C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
2. Unsaturated fatty acids: double bonds
(good)
O
unsaturated C-CH2-CH2-CH2-CH
21
Proteins
22
Proteins (Polypeptides)
• Amino acids (20 different kinds of aa) are
bonded together by peptide bonds
(polypeptides).
• Six functions of proteins:
1. Storage:
albumin (egg white)
2. Transport:
hemoglobin
3. Regulatory:
hormones
4. Movement:
muscles
5. Structural:
membranes, hair, nails
6. Enzymes:
cellular reactions
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Proteins (Polypeptides)
Four levels of protein structure:
A.Primary Structure
B. Secondary Structure
C. Tertiary Structure
D.Quaternary Structure
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Primary Structure
Amino acids bonded together
by peptide bonds (straight
chains)
Amino Acids (aa)
aa1
aa2
aa3
aa4
aa5
aa6
Peptide Bonds
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Secondary Structure
• 3-dimensional folding arrangement of a
primary structure into coils and pleats
held together by hydrogen bonds.
• Two examples:
Alpha Helix
Beta Pleated Sheet
Hydrogen Bonds
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Tertiary Structure
• Secondary structure is bent and folded
into a more complex 3-D arrangement
of linked polypeptides
• Bonds: H-bonds, ionic, disulfide
bridges (S-S)
• Call a “subunit”.
Alpha Helix
Beta Pleated Sheet
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Quaternary Structure
• Composed of 2 or more
“subunits”
• Globular in shape
• Form in Aqueous environments
• Example: enzymes (hemoglobin)
subunits
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Nucleic
Acids
29
Nucleic acids
• Two types:
a. Deoxyribonucleic acid (DNAdouble helix)
b. Ribonucleic acid (RNA-single
strand)
• Nucleic acids are composed of long chains of
nucleotides linked by dehydration synthesis.
• A typical cell in your body has about 2
meters of DNA
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Nucleic acids
• Nucleotides include:
phosphate group
pentose sugar (5-carbon)
nitrogenous bases:
adenine (A)
thymine (T) DNA only
uracil (U) RNA only
cytosine (C)
guanine (G)
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Nucleotide
Phosphate
Group
O
O=P-O
O
5
CH2
O
N
C1
C4
Nitrogenous base
(A, G, C, or T)
Sugar
(deoxyribose)
C3
C2
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5
DNA
double
helix
O
3
3
O
P
5
O
C
G
1
P
5
3
2
4
4
2
3
1
P
T
5
A
P
3
O
O
P
5
O
3
5
P
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